If the sausage is floppy like a noodle or if the juices are pink in color, your sausage needs more time.
In general, you can eat a sausage if it’s still slightly pink on the inside (since eating underdone beef and pork is usually fine). However, the sausage should be mostly brown or taupe inside.
You can also poach your sausages in wine, chicken stock, or beer for added flavor.
The fat from the sausages will run out onto the pan as they cook, making the sausages even less likely to stick to the pan.
Regularly turning the sausages also helps them cook thoroughly.